Blasting apparatus and blasting method

ABSTRACT

A fusible and vaporizable substance (for example, a thin metal wire is used)  2  is fused and vaporized by supplying thereto a predetermined amount of electrical energy from a capacitor  14  of an electrical energy supply circuit  10  for a short period of time, and nitromethane  3  is detonated by a phenomenon in the process in which the fusible and vaporizable substance  2  fuses and vaporizes, so that an object to be blasted  4  is reliably blasted by this detonation force.

TECHNICAL FIELD

The present invention relates to a blasting apparatus and a blastingmethod in which a fusible and vaporizable substance (for example, a thinmetal wire is used) is fused and vaporized by supplying electricalenergy to the fusible and vaporizable substance for a short period oftime, and nitromethane is detonated by a phenomenon in the processaccompanying this fusing and vaporizing, whereby an object to be blastedsuch as a concrete structure and rock-bed is blasted.

1. Background Art

There has conventionally been available a blasting apparatus forblasting an object to be blasted such as a concrete structure androck-bed, which has dynamite and a detonator used as means fordetonating the dynamite.

The dynamite uses a low explosive which is not readily detonated whensome impact force is applied or when fire is taken in order to assuresafety in handling. For this reason, the detonator is filled with anexplosive which is detonated relatively easily. The explosive charged inthe detonator is detonated by fire or electrical spark, and the lowexplosive used in the dynamite is detonated by a shock occurring at thistime. However, since the detonator is filled with an explosive which isdetonated relatively easily, there is a danger that the detonator willbe detonated if a leak current from an equipment around the storageplace, a surge current, a thunderbolt or the like occurs and such acurrent is supplied to the detonator.

Accordingly, an object of the present invention is to provide a blastingapparatus and a blasting method which can solve the above problem.

2. Disclosure of the Invention

The present invention provides a blasting apparatus comprising ablasting vessel charged with nitromethane and mounted in an object to beblasted, a fusible and vaporizable substance which is exposedly providedin this nitromethane and suddenly fuses and vaporizes by being suppliedwith a predetermined amount of electrical energy for a short period oftime, and an electrical energy supply circuit having a capacitor foraccumulating the predetermined amount of electrical energy to besupplied to the fusible and vaporizable substance, wherein when thepredetermined amount of electrical energy is supplied, the nitromethaneis detonated by a phenomenon in the process in which the fusible andvaporizable substance fuses and vaporizes, so that the object to beblasted is blasted by the detonation force.

According to the configuration of the present invention, when thepredetermined amount of electrical energy is accumulated in thecapacitor, and the electrical energy is supplied from the electricalenergy supply circuit to the fusible and vaporizable substance, thefusible and vaporizable substance suddenly fuses and vaporizes, and thenitromethane is detonated by a phenomenon in the process in which thefusible and vaporizable substance fuses and vaporizes, so that theobject to be blasted is blasted by this detonation force. Even if a leakcurrent from a surrounding equipment occurs, the nitromethane is notdetonated unless electrical energy enough to fuse and vaporize thefusible and vaporizable substance is supplied, so that the safety inhanding the blasting apparatus can be improved.

Also, the present invention provides a blasting apparatus usingnitromethane. In this case as well, since the nitromethane is notdetonated unless electrical energy enough to fuse and vaporize thefusible and vaporizable substance is supplied, the safety in handing theblasting apparatus is improved, and since a strong blasting force isobtained by detonating the nitromethane, the object to be blasted cansurely be blasted or made brittle.

Also, the present invention provides a blasting method comprising thesteps of exposedly providing a fusible and vaporizable substance innitromethane charged in a blasting vessel, said fusible and vaporizablesubstance suddenly fusing and vaporizing by being supplied with apredetermined amount of electrical energy for a short period of time,supplying electrical energy enough to fuse and vaporize the fusible andvaporizable substance to this fusible and vaporizable substance from acapacitor, and detonating the nitromethane by a phenomenon in theprocess in which the fusible and vaporizable substance fuses andvaporizes so that an object to be blasted is blasted by this detonationforce, wherein as conditions for detonating the nitromethane, thecharging voltage V_(c) (V), charging energy W (J) and capacitance C (F)of the capacitor are set to have the following relationship:

V _(c)≧1000  (V)

W=(½)·C· V _(c) ²≧250  (J)

By thus setting the relationship of the charging voltage V_(c) (V),charging energy W (J) and capacitance C (F) of the capacitor, thenitromethane near the fusible and vaporizable substance is detonatedwithout fail, and the remaining nitromethane is detonated in successionby the resultant impact force, whereby the object to be blasted isblasted without fail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the whole configuration of a blastingapparatus in accordance with an embodiment of the present invention,including a sectional view showing a state in which a blasting vessel ismounted in a mounting hole in an object to be blasted; and

FIG. 2 is an enlarged sectional view showing a state in which theblasting vessel is mounted in the mounting hole in the object to beblasted.

BEST MODE FOR CARRYING OUT THE INVENTION

In order to explain the present invention in detail, one embodiment willbe described with reference to the accompanying drawings, FIGS. 1 and 2.

For a blasting apparatus 1 in accordance with an embodiment of thepresent invention, as one example of a fusible and vaporizablesubstance, a thin metal wire 2 formed of copper (Cu) with a diameter of0.3 mm is suddenly fused and vaporized, and nitromethane 3 is detonatedby an impact force generated by a phenomenon accompanying the process inwhich the fusible and vaporizable substance fuses and vaporizes, suchphenomenon being as electric discharge, spark, heat generation, andevaporative expansion, whereby an object to be blasted 4 such as aconcrete structure or rock-bed is blasted.

Also, in the blasting apparatus 1 in accordance with the embodiment ofthe present invention, the nitromethane 3 is charged in a blastingvessel 6 which is mounted in a mounting hole 5 formed in the object tobe blasted 4, and the open side of the blasting vessel 6 is sealed by acover member 7. A pair of electrodes 8 are inserted in the cover member7, and the tip ends of these electrodes 8 are connected to each othervia the thin metal wire 2 exposed to the nitromethane 3. As material forthe blasting vessel 6, a nonmetal material such as wood, paper orsynthetic resin, or a metal such as aluminum or iron is used.

There is provided an electrical energy supply circuit 10 which isconnected to the thin metal wire 2. This electrical energy supplycircuit 10 supplies to the thin metal wire 2 a predetermined amount ofelectrical energy enough to fuse and vaporize the thin metal wire 2.

The electrical energy supply circuit 10 comprises a power source 11connected between terminals 8 a of the electrodes 8, a capacitor 14connected in parallel between the power source 11 and the terminals 8 a,a charge control circuit 12 connected between the power source 11 andone of the terminals 8 a to control that a predetermined amount ofelectrical energy is accumulated in the capacitor 14, and a dischargeswitch 13 connected between the charge control circuit 12 and one of theterminals 8 a.

The blasting apparatus 1 of the above configuration is manufactured byconnecting the tip ends of both the electrodes 8 to each other with thethin metal wire 2 , inserting the electrodes 8 in the cover member 7,charging the nitromethane 3 in the blasting vessel 6, sealing thenitromethane 3 by installing the cover member 7 in the blasting vessel6, and connecting the electrical energy supply circuit 10 to theterminals 8 a of both the electrodes 8.

In order to blast the object to be blasted 4, the blasting vessel 6 ismounted in the mounting hole 5 formed in the object to be blasted 4, thepredetermined amount of electrical energy necessary to fuse and vaporizethe thin metal wire 2 is accumulated in the capacitor 14, and then thedischarge switch 13 is turned on. Thereby, the electrical energy issupplied to the thin metal wire 2 for a short period of time, so thatthe thin metal wire 2 is suddenly fused and vaporized. The nitromethane3 is detonated by the phenomenon accompanying the process in which thethin metal wire 2 fuses and vaporizes. The detonation force of thenitromethane 3 is added to the impact force generated when the thinmetal wire 2 is fused and vaporized, so that the object to be blasted 4is surely blasted or made brittle.

Thus, the mode for carrying out the present invention is such that thenitromethane 3 is charged in the blasting vessel 6, the thin metal wire2 connected between the electrodes 8 is used in place of a detonator,and the predetermined amount of electrical energy is supplied to thethin metal wire 2 to fuse and vaporize it. Therefore, even if a leakcurrent from a surrounding equipment is supplied to the thin metal wire2, the nitromethane 3 is not detonated unless electrical energy enoughto fuse and vaporize the thin metal wire 2 is supplied, so that theblasting apparatus 1 can be handled safely.

Here, an impact force F necessary for detonating the nitromethane 3 isabout 70 ton·f/cm².

The impact force F (ton·f/cm²) provided by the thin metal wire 2 isgenerated under the following condition:

F=0.008·W/L  (1)

W=(½)·C·V _(c) ²  (2)

In the above equations (1) and (2), W is charging energy (J) of thecapacitor, L is a distance (cm) from the thin metal wire 2, V_(c) is acharging voltage (V) of the capacitor, and C is a capacitance (F) of thecapacitor.

Since the impact force F necessary for detonating the nitromethane 3 isabout 70 ton·f/cm² as described above, it is necessary just to set thevalues of W, L, V_(c) and C to obtain the necessary impact force on thebasis of the above equations (1) and (2).

If part of the nitromethane 3 in the blasting vessel 6 is detonated, thedetonation proceeds in succession by the impact force (this is calledpropagation of detonation). Therefore, detonation of a small portionnear the thin metal wire 2 suffices to detonate all of the nitromethane3 charged in the blasting vessel 6. However, in the case where V_(c) (orW) is low, even if the impact force F necessary for detonation isgenerated on the basis of the above equations (1) and (2), it is knownthat the nitromethane 3 will not detonated. The reason for this isconsidered to be that not only the impact force but energy over apredetermined amount is needed to detonate the nitromethane 3.Thereupon, a detonation experiment was made on the nitromethane 3 usingthe energy necessary for detonating the nitromethane 3 as a parameter ofthe charging energy. The table below gives the experimental results.

Vc(V) C(μF) W(J) Weight(g) State of detonation 500 500 62.5 100 Notdetonated 900 500 202.5 100 Not detonated 1000 500 250 100 Verypartially detonated 1500 500 562.5 100 Partially detonated 1600 500 640100 Detonated by half 1700 500 722.5 100 Completely detonated 1800 500810 100 Completely detonated 2000 500 1000 100 Completely detonated

From the above table, the conditions for detonating the nitromethane 3are as follows:

V _(c)≦1000[V]

W=(½)·C·V _(c) ²≧250[J]

Under these conditions, all of the nitromethane 3 in the blasting vessel6 can be detonated.

Although an example in which the thin metal wire 2 is used as oneexample of the fusible and vaporizable substance has been explained inthe above-described embodiment, the present invention is not limited tothis. For example, a small metallic piece or a conductive material suchas carbon formed into an appropriate shape may be used. If any of theaformentioned material is used, like in the above-described embodiment,the nitromethane 3 is detonated by the phenomenon in the process inwhich the fusible and vaporizable substance is fused and vaporized, bywhich the object to be blasted 4 is surely blasted or made brittle.Other operations and effects are the same as those of theabove-described embodiment, so that the explanation thereof is omitted.

Also, although the blasting vessel 6 is used so as to be mounted in themounting hole 5 formed in the object to be blasted 4 in theabove-described embodiment, the present invention is not limited tothis. The blasting vessel 6 can be used in such a manner as being placedin contact with the surface of the object to be blasted 4 or being hungto be placed near the surface of the object to be blasted 4 by using ahanging means. In any case, the thin metal wire 2 (small metallic pieceor conductive material such as carbon) is suddenly fused and vaporizedby being supplied with electrical energy for a short period of time, andthe nitromethane 3 is detonated by the phenomenon accompanying theprocess in which the thin metal wire 2 fuses and vaporizes, so that theobject to be blasted 4 can be blasted or made brittle by the impactforce generated when the thin metal wire 2 is fused and vaporized andthe detonation force of the nitromethane 3.

Further, the blasting apparatus 1 can be used as a hypocentral apparatusfor geophysical exploration by regulating the blasting force in theblasting apparatus 1 of the above mode.

INDUSTRIAL APPLICABILITY

As described above, the blasting apparatus and the blasting method inaccordance with the present invention is suitable to blast an object tobe blasted which requires a large blasting force in blasting.

What is claimed is:
 1. A blasting apparatus comprising a blasting vesselwhich is charged with nitromethane, a fusible and vaporizable substancewhich is exposedly provided in this nitromethane and suddenly fuses andvaporizes by being supplied with a predetermined amount of electricalenergy for a short period of time, and an electrical energy supplycircuit having a capacitor for accumulating electrical energy to besupplied to the fusible and vaporizable substance, wherein thenitromethane is detonated by a phenomenon in the process in which thefusible and vaporizable substance fuses and vaporizes, so that an objectto be blasted is blasted by this detonation force.
 2. A blasting methodcomprising the steps of exposedly providing a fusible and vaporizablesubstance in nitromethane charged in a blasting vessel, said fusible andvaporizable substance suddenly fusing and vaporizing by being suppliedwith a predetermined amount of electrical energy for a short period oftime, supplying electrical energy enough to fuse and vaporize thefusible and vaporizable substance to this fusible and vaporizablesubstance from a capacitor, and detonating the nitromethane by aphenomenon in the process in which the fusible and vaporizable substancefuses and vaporizes, so that an object to be blasted is blasted by thisdetonation force, wherein as conditions for detonating the nitromethane,the charging voltage V_(c) (V), charging energy W (J) and capacitance C(F) of the capacitor are set to have the following relationship: V_(c)≧1000  (V) W=(½)·C·V _(c) ²250  (J).